The present invention relates to a method and apparatus for automatically detecting the presence of defects in transparent containers, particularly those produced from glass. In particular, the present invention is directed to the automatic detection of defects located in or near the bottom of a transparent container.
Transparent containers, such as glass bottles and the like, are subject to a number of different types of defective conditions. Such defective conditions, which may be present in the bottom of the container or the lower portion of the side wall, could include fissures, split heels, split bottoms, internal stuck glass, internal loose glass, external stuck glass, impacted baffles, foreign objects or materials, tears, blisters, and the like.
The containers must either be individually inspected by human inspectors to reject those having a defect condition, or inspected by any of various types of known automatic systems that have been proposed for inspecting various defects. Examples of inspection systems relating to container bottom inspection include those disclosed in U.S. Pat. Nos. 3,557,950 and 3,101,848. In the systems disclosed in these patents, each container is stopped in its path of travel and rotated while a spot on it is illuminated with a beam of light. In another type of inspection system disclosed in U.S. Pat. No. 3,746,165, the container continuously moves through an inspection system while its entire bottom is illuminated with diffused light.
In another known type of inspection system, a plurality of containers rotate and continuously move through an inspection zone. A line of light from a light source is directed at a mirror which reflects the light through the side wall toward and across the bottom of the containers to be inspected. The reflected light which passes through the bottom of the container can again be reflected by defects or objects in or on the bottom of the container. This additionally reflected light can then be detected by a line scan camera.
While these known systems are capable of detecting at least some defects in or associated with the bottom of a transparent container, it is desirable to provide an inspection system which provides greater reliability and efficiency in the detection of defects, particularly those defective conditions associated with the interior bottom surface of the container. Such defects would include, for example, internal stuck glass, internal loose glass or foreign material.